<p>Failing to explicitly declare the visibility of a member variable could result it in having a visibility you don't expect, and potentially leave it open to unexpected modification by other classes.</p>

<h2>Noncompliant Code Sample</h2>
<pre>
class Ball {
  String color="red";  // Noncompliant
}
enum A {
 B;
 int a;
}
</pre>

<h2>Compliant Solution</h2>
<pre>
class Ball {
  private String color="red";  // Compliant
}
enum A {
 B;
 private int a;
}
</pre>
